TALLADEGA, Ala. — Tony Stewart tried to block his way to victory at Talladega Superspeedway. It backfired, badly.

The "big one" came on the last lap Sunday, when Stewart's attempt to hold on for the win instead sent his car sailing through the field and triggered a 25-car accident. Daytona 500 winner Matt Kenseth won under caution, and everyone else was left wondering what happened to cause so much carnage.